This invention relates generally to the control of fluid flow in a well and more particularly concerns the utilization of fluid pressure at the surface to independently control a valve at a subsurface location to control the flow of production fluid streams both inside and outside the tubing strings.
In the completion, production and treating of oil and gas wells, it sometimes becomes desirable to control the flow of production from more than one zone and in fact in some oil wells, it is desirable to obtain production from three separate and independent zones and it is desirable to have control over the flow from those various zones. One way of obtaining production from three zones is to utilize three independent tubing strings within one well casing. It should be obvious that insertion of three cylindrical tubing strings inside an originally cylindrical casing sacrifices a great deal of the cross-sectional area of the casing which cannot thereafter be used for production flow, and consequently, the production flow is drastically reduced. An alternative to separate tubing strings to each production zone has been the use of a combination of tubing string flow to one or two zones, using the annulus between the casing and the tubing string or strings to receive production flow from another zone. There are a number of devices utilized for the control of flow in the tubing and in the annulus. One such device is the patent of J. S. Page, Jr., U.S. Pat. No. 3,313,350 which is a tubing and annulus flow control apparatus which is wire-line retrievable. The manner in which that device functions differs materially from the present invention in that independent control of the two flow paths is not possible. In addition, because no control line to the surface is utilized therein, that device provides no safety features. Additionally, the present invention provides the user with options in the use of the device to afford him the ability to control either the casing flow or both the casing flow and the tubing string flow independently, or the casing flow and two independent tubing string flows while also providing a safety feature to each of those production zones which will automatically shut each zone in in the event there is a loss of control line pressure as the result of some damage to the control line linkage. The basic structure of the valve which provides for annulus flow control also is provided with a mechanical actuating device to open or close the valve in the event that there is damage to the control line.